Irrelevant-incentive learning under hunger and thirst as assessed by discrimination transfer.

Two groups of 64 male albino rats received 2 food (F) and 2 water (W) rewarded trials daily in the alternating sequence FWFW. One group was hungry in Phase I and thirsty in Phase II (HA-TA) while the other was thirsty in Phase I and hungry in Phase II (TA-HA). As assessed by the rate of development of appropriate pattern running in Phase II, HA-TA demonstrated positive transfer and TA-HA negative transfer relative to controls. It is concluded that in addition to learning excitatory and inhibitory habits in Phase I, hungry Ss also learned expectancies regarding the ordering of specific rewards which facilitated the development of appropriate patterning in Phase II. Thirsty Ss either failed to learn specific reward expectancies in Phase I, or if formed, the facilitative effect of these expectancies on Phase II performance was masked by a strong inhibitory habit learned in Phase I. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interaction of hunger and thirst in the motivational arousal underlying hoarding behavior in the rat.

Conducted 3 experiments with 25 male Wistar rats in which hoarding of food could be elicited by a 16-hr food deprivation schedule. It was found that (a) prolonged water restriction, with food ad lib, failed to induce hoarding in spite of spontaneous reduction in food intake and a fall in body weight to below levels normally critical for the onset of hoarding. Thus, different physiological deficits are not necessarily equivalent or additive in elicitation of food hoarding, and water lack may suppress it. (b) Hoarding behavior was released in water-deprived Ss by a drink of water. A 30-min delay to allow absorption of the water significantly enhanced the release of hoarding. Air drinking by water-deprived Ss did not release hoarding. Thus, absence of hoarding during water lack may be caused by an active process that can be inhibited or canceled by postingestional effects of drinking but not by oropharyngeal stimulation mimicking water signals. (c) Although water lack prevented hoarding in response to self-imposed fasting, hoarding ensued at maximal rates when further food deprivation was superimposed. Thus, inhibition of hoarding by dehydration operates subtractively, not multiplicatively, and with free access to food, the inhibition of hoarding by thirst tends to be balanced exactly by the facilitatory effect of concomitant fasting; thus superadded food deprivation can take full effect. It is concluded that in states of motivational arousal, specific inhibitory mechanisms may inhibit subtractively certain activities biologically irrelevant to prevailing physiological needs. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associations between Pavlovian CSs and context.

Three experiments, with 48 female Carneaux pigeons, used autoshaping procedures to assess associations between Pavlovian CSs and the contexts in which they occur. Three contexts were identified by different visual wall patterns; conditioning of those contexts was assessed by the amount of general activity in their presence. Exp I found that key-light CSs given discriminative autoshaping with food in 1 context could differentially 2nd-order conditioned activity to 2 new contexts. Exp II used a sensory preconditioning procedure to detect associations between 2 contexts and neutral key lights given in their presence. When those key lights were differentially paired with food in a 3rd context, activity changed differentially in the original 2 contexts. Exp III found that if 2 key lights were paired with food in 2 different contexts, differential extinction of those key lights induced differential activity in their contexts. Consequently, CSs that are either previously conditioned, neutral, or currently undergoing conditioning all become associated with the context in which they appear. Exps II and III found that the changes in context value induced by manipulation of the key lights influenced learning and performance to other CSs. A context that was made valuable through manipulation of its CS was better able to block conditioning to another CS but also better able to promote performance to previously trained CSs. Results agree with outcomes of direct conditioning of a context by a UCS and suggest that CS-induced changes in context are quite powerful. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Pavlovian analysis of goal-directed behavior.

The associative structures underlying goal-directed behavior are analyzed using techniques that are well-developed for studying Pavlovian conditioning. The analysis helps identify the roles of the stimulus, response, and reinforcer in instrumental learning. The results point to the basic importance of an association between a response and its reinforcer in the acquisition and maintenance of instrumental behavior. They also suggest that the stimulus may play a variety of roles through its association with the response and the reinforcer and through its setting the occasion on which the response is associated with the reinforcer. This research illustrates the use of Pavlovian techniques for the exploration of other forms of learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of the relation between Pavlovian occasion-setting and instrumental discriminative stimuli: A blocking analysis.

Retracted October 1990. (See record 1991-03475-001.) Conducted 2 experiments with 72 male Sprague-Dawley rats, using a blocking design (A+, then AB+) to assess the relation between Pavlovian occasion-setting and instrumental discriminative stimuli. Prior conditioning of both associative and occasion-setting functions of A in a serial feature-positive procedure blocked acquisition of an instrumental discriminative function by a novel stimulus (B) trained in compound with A. Neither prior conditioning of only an A/unconditioned stimulus/stimuli (UCS) association nor prior conditioning of Stimulus A using a Pavlovian simultaneous feature-positive procedure, which does not endow A with an occasion-setting function, blocked acquisition of an instrumental discriminative function by B. Prior acquisition of an instrumental discriminative function by A blocked acquisition of a Pavlovian occasion-setting function by a novel stimulus (B) trained in compound with A but did not block acquisition of an association between B and the UCS. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian conditioned inhibition.

Examined the notion of conditioned inhibition and suggests a definition in terms of the learned ability of a stimulus to control a response tendency opposed to excitation. 2 techniques of measuring inhibition are outlined: (1) the summation procedure in which an inhibitor reduces the response that would normally be elicited by another stimulus, and (2) the retardation of acquisition procedure in which an inhibitor is retarded in the acquisition of an excitatory CR. Examples of the use of these procedures are given for a variety of UCS modalities. Several possible operations for generating conditioned inhibitors are reviewed: extinction following excitatory conditioning, discriminative conditioning, arrangement of a negative correlation between CS and a UCS, use of an extended CS-UCS interval, and presentation of a stimulus in conjunction with UCS termination. These operations suggest that conditioned inhibitors are not generated either by simple extinction procedures or by pairing a stimulus with UCS termination. By contrast, for both salivary and fear conditioning the other procedures do appear to generate inhibitors. Most of the procedures generating conditioned inhibitors can be described as arranging a negatively correlated CS and UCS. (2 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian contingencies and temporal information.

The effects of altering the contingency between the conditioned stimulus (CS) and the unconditioned stimulus (US) on the acquisition of autoshaped responding was investigated by changing the frequency of unsignaled USs during the intertrial interval. The addition of the unsignaled USs had an effect on acquisition speed comparable with that of massing trials. The effects of these manipulations can be understood in terms of their effect on the amount of information (number of bits) that the average CS conveys to the subject about the timing of the next US. The number of reinforced CSs prior to acquisition is inversely related to the information content of the CS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An analysis of the relationship between hydration and protein-DNA interactions

Eleven protein-DNA crystal structures were analyzed to test the hypothesis that hydration sites predicted in the first hydration shell of DNA mark the positions where protein residues hydrogen-bond to DNA. For nine of those structures, protein atoms, which form hydrogen bonds to DNA bases, were found within 1.5 A of the predicted hydration positions in 86% of the interactions. The correspondence of the predicted hydration sites with the hydrogen-bonded protein side chains was significantly higher for bases inside the conserved DNA recognition sequences than outside those regions. In two CAP-DNA complexes, predicted base hydration sites correctly marked 71% (within 1.5 A) of protein atoms, which form hydrogen bonds to DNA bases. Phosphate hydration was compared to actual protein binding sites in one CAP-DNA complex with 78% marked contacts within 2.0 A. These data suggest that hydration sites mark the binding sites at protein-DNA interfaces.     

Pavlovian second-order conditioned analgesia.

Three experiments, with 118 Sprague-Dawley rats, assessed conditioned analgesia in a Pavlovian 2nd-order conditioning procedure by using inhibition of responding to thermal stimulation as an index of pain sensitivity. In Exp I, Ss receiving 2nd-order conditioning showed longer response latencies during a test of pain sensitivity in the presence of the 2nd-order conditioned stimulus (CS) than Ss receiving appropriate control procedures. Exp II found that extinction of the 1st-order CS had no effect on established 2nd-order conditioned analgesia. Exp III evaluated the effects of post 2nd-order conditioning pairings of subcutaneous morphine sulfate (10–20 mg/kg) and the shock unconditioned stimulus/stimuli (UCS). Ss receiving paired morphine–shock presentations showed significantly shorter response latencies during a hot-plate test of pain sensitivity in the presence of the 2nd-order CS than did Ss receiving various control procedures; 2nd-order analgesia was attenuated. Data extend the associative account of conditioned analgesia to 2nd-order conditioning situations and are discussed in terms of the mediation of both 1st- and 2nd-order analgesia by an association between the CS and a representation or expectancy of the UCS, which may directly activate endogenous pain inhibition systems. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Primary polydipsia. Syndrome of inappropriate thirst

A patient with lifelong severe polyuria and polydipsia had normal serum antidiuretic hormone (ADH) levels and responded to water deprivation with a prompt increase in urine osmolality and maintenance of normal plasma osmolality (less than 290 mOsm/kg), despite extreme thirst. When treated with desmopressin acetate and allowed free access to water, she was able to reduce plasma osmolality below 270 mOsm/kg, and her compelling thirst disappeared. The disorder is interpreted to be the result of excessive fluid intake in response to a thirst stimulus that was not inhibited by normal plasma osmolality. This study indicates that osmoreceptor control of ADH secretion is normal. Continued administration of vasopressin has relieved the symptoms and has not resulted in water intoxication.     

Extinction of Pavlovian conditioned inhibition.

Examined 2 procedures with potential for reducing Pavlovian conditioned inhibition in 4 experiments with 72 male Sprague-Dawley rats. The 1st, simple nonreinforced presentation, was suggested by a theory which has been successful with data from the acquisition of conditioned inhibition. However, nonreinforced presentation of a stimulus, either after conditioned inhibition training or intermixed with such training, failed to produce any loss of the inhibition controlled by that stimulus. The 2nd procedure involved removing the negative correlation between inhibitor and reinforcement. When this correlation was altered, in such a way as to continue UCS presentation, loss of inhibition occurred. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retraining of extinguished Pavlovian stimuli.

Five Pavlovian magazine approach experiments with rat subjects examined the mechanism by which reconditioning restores extinguished responding. Experiments 1, 2, and 3 found that retraining did not destroy the spontaneous recovery with the passage of time that is characteristic of extinguished stimuli. Experiments 4 and 5 found evidence that retraining after extinction enhanced the strength of the originally trained associations. Together these results suggest that, just as extinction does not destroy original acquisition but superimposes some decremental process, so retraining does not destroy that decremental process but instead superimposes further associative learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ethanol enhancement of Pavlovian conditioning.

60 New Zealand albino rabbits were tested for Pavlovian conditioning and extinction of eye-blink (EB) and heart-rate (HR) responses following water or various doses of oral ethanol (375–2,500 mg/kg). The highest dose suppressed both EB and HR conditioning during training, whereas the lowest dose enhanced HR responses during training and increased EB responses during later extinction in a symmetrically state-dependent manner. An intermediate dose (750 mg/kg) administered during training enhanced HR responses and suppressed EB responses but increased EB responses during later extinction following either ethanol or water. Ethanol treatments also suppressed unconditioned responses (UCRs) to shock and increased locomotor activity; however, these effects differed qualitatively from those that ocurred during Pavlovian training and extinction. Results suggest that very low doses of ethanol can enhance the ability of stimuli to elicit Pavlovian conditioned reflexes and impair the ability to adaptively modify these reflexes when stimulus contingencies later change. (55 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unblocking in Pavlovian appetitive conditioning.

Two experiments, with 280 Sprague-Dawley rats, demonstrated unblocking in an appetitive conditioning preparation. One stimulus, A, was first paired with either a low-value reinforcer (1 food pellet) or a high-value reinforcer (1 food pellet followed by 2 more food pellets). A 2nd stimulus, X, was then added to A, and the compound was reinforced with either the high- or low-value reinforcer. Conditioning to X was blocked if the same reinforcer was used in both phases of the experiment, but there was substantial conditioning to X when the reinforcer value was shifted either up or down when X was introduced. Exp I demonstrated this unblocking phenomenon using a design that minimized the potential contribution of generalization decrement. Exp II examined the effects of a variety of posttraining manipulations on conditioned responding to the added X cue after unblocking procedures. Among Ss that received downshifts in reinforcer value when X was introduced, responding was affected by several posttraining manipulations, including changes in context value. Those manipulations had smaller effects on the responding of Ss that received upshifts in reinforcer value and no effects on responding in control conditions. Findings are considered in relation to the model of conditioning outlined by R. A. Rescorla and A. R. Wagner (1972). (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unblocking in Pavlovian fear conditioning.

Six experiments used rats to study blocking and unblocking of fear learning. An excitatory stimulus (A) blocked fear learning to a neutral stimulus (B). Unblocking of B occurred if the AB compound signaled an increase in unconditioned stimulus (US) intensity or number. Assessments of associative change during blocking showed that more was learned about B than A. Such assessments during unblocking revealed that more was learned about B than A following an increase in US intensity but not US number. These US manipulations had no differential effects on single-cue learning. The results show that variations in US intensity or number produce unblocking of fear learning, but for each there is a different profile of associative change and a potentially different mechanism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Potentiation and overshadowing in Pavlovian fear conditioning.

The present experiments addressed a fundamental discrepancy in the Pavlovian conditioning literature concerning responding to a target cue following compound reinforced training with another cue of higher salience. Experiment 1 identified one determinant of whether the target cue will be overshadowed or potentiated by the more salient cue, namely contiguity between compound CS termination and US presentation. Overshadowing and potentiation were observed with delay and trace procedures, respectively. Experiments 2 and 3 contrasted elemental and configural explanations of potentiation. Both experiments supported a configural account. Experiments 3 and 4, by manipulating prior learning experiences to bias subjects to encode the same compound elementally or configurally, demonstrated decreased potentiation and overshadowing, respectively. Overall, these experiments demonstrate potentiation with nontaste stimuli and identify one variable that determines whether overshadowing or potentiation will occur. Moreover, they show that prior experiences can determine how a compound is encoded and are compatible with the idea of flexible encoding as a principle of information processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibitory interactions between appetitive and aversive stimuli.

Reviews the behavioral evidence that a stimulus of a given affective value will exert a central inhibitory influence on responding maintained by stimuli of the opposite affective value. The effects of aversive stimuli on appetitively motivated behavior and of appetitive stimuli on aversively motivated behavior are considered separately. The evidence for a true inhibitory action is evaluated in terms of 3 behavioral criteria: the summation, retardation, and counterconditioning tests. Special attention is paid to the role of peripheral response interactions in determining the outcome of these tests. Although aversive stimuli meet all 3 criteria as inhibitors of appetitive behavior, the evidence that appetitive stimuli inhibit aversively motivated behavior is far less consistent. The strongest evidence for the inhibitory effect of appetitive stimuli comes from studies attempting to countercondition the reinforcing properties of aversive stimuli. It is concluded that this line of research supports general motivational theories that argue for the functional equivalence of excitors and inhibitors of opposite affective value. (4? p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual interactions between musical pitch and timbre.

Three experiments examined perceptual interactions between musical pitch and timbre. Exp 1, through the use of the Garner classification tasks, found that pitch and timbre of isolated tones interact. Classification times showed interference from uncorrelated variation in the irrelevant attribute and facilitation from correlated variation; the effects were symmetrical. Exps 2 and 3 examined how musical pitch and timbre function in longer sequences. In recognition memory tasks, a target tone always appeared in a fixed position in the sequences, and listeners were instructed to attend to either its pitch or its timbre. For successive tones, no interactions between timbre and pitch were found. That is, changing the pitches of context tones did not affect timbre recognition, and vice versa. The tendency to perceive pitch in relation to other context pitches was strong and unaffected by whether timbre was constant or varying. In contrast, the relative perception of timbre was weak and was found only when pitch was constant. These results suggest that timbre is perceived more in absolute than in relative terms. Perceptual implications for creating patterns in music with timbre variations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparator view of Pavlovian and differential inhibition.

In 3 experiments using rats as subjects, the authors varied trial spacing to investigate the conditions under which Pavlovian and differential inhibition are observed. Experiment 1 compared Pavlovian and differential inhibition with spaced training trials. Spaced trials resulted in only the Pavlovian inhibitor passing both summation and retardation tests. Conversely, Experiment 2 compared these 2 types of inhibition with massed training trials. This training resulted in only the differential inhibitor passing both tests for conditioned inhibition. Finally, in Experiment 3 all subjects experienced Pavlovian inhibition training with massed trials. Although this training by itself did not result in behavior indicative of inhibition, subjects that also experienced posttraining extinction of the training context did pass both tests for inhibition. Overall, these results are anticipated by the extended comparator hypothesis (Denniston, Savastano, & Miller, 2001) but are problematic for most contemporary associative learning theories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proactive interference between cues trained with a common outcome in first-order Pavlovian conditioning.

The nature of interference between cues (X, A) trained apart with a common outcome (O; an unconditioned stimulus) was explored by assessing proactive interference in first-order Pavlovian conditioning (i.e., A-O, X-O, resulting in attenuated responding to X). Three lick-suppression studies were conducted with water-deprived rats. Posttraining extinction of the interfering cue (A) attenuated proactive interference (Experiment 1), which mirrors the observation that extinction of the competing cue can reduce competition between cues trained together (e.g., recovery from overshadowing). Proactive interference was also attenuated with manipulations known to attenuate interference between outcomes trained apart (e.g., counterconditioning), namely reminder cues (Experiment 2) and renewal (Experiment 3). The findings suggest that similar processes underlie interference between cues trained apart, between cues trained together, and between outcomes trained apart. (PsycINFO Database Record (c) 2010 APA, all rights reserved)